Water-in-oil emulsions

ABSTRACT

DIALKYLAMINOALKANOLS ARE EFFECTIVE AS EMULSION STABILIZERS IN WATER-IN-OIL EMULSIONS FORMED WITH APOLYALKENYL SUCCINIC ANHYDRIDE EMULSIFYING AGENT.

United States Patent 3,629,119 WATER-IN-OIL EMULSIONS John J. Weaver, Edwardsville, Ill., assignor to Shell Oil Company, New York, NY. No Drawing. Filed Dec. 22, 1969, Ser. No. 887,353 Int. Cl. B01f 17/16; C09k 3/00 US. Cl. 252-77 5 Claims ABSTRACT OF THE DISCLOSURE Dialkylaminoalkanols are elfective as emulsion stabilizers in water-in-oil emulsions formed with a polyalkenyl succinic anhydride emulsifying agent.

This invention relates to improved water-in-oil emulsions. More particularly, the invention relates to emulsions having a high degree of stability over extended periods of storage or use.

Hydraulic fluids based on Water-in-oil emulsions have found widespread application in a number of industries because of their relatively low cost and fire-resistant properties. The effectiveness of these fluids is, of course, dependent on their remaining in an emulsified state. If separation occurs to any large degree, the lubricating and fire-resistant characteristics of the fluids immediately diminish, necessitating their replacement.

In response to this need for more stable emulsions, a number of emulsifying agents and combinations thereof have been proposed, among the most effective of which is the combination of a polyalkenyl succinic anhydride with a polyalkoxylated partial ester of a polyhydric alcohol such as polyoxyethylene sorbitan mono-oleate. While succinic anhydrides have been effectively employed with other emulsifying agents as co-emulsifiers, they generally do not form suitable emulsions when employed as the sole emulsifying agent.

It has now been found that a dialkylaminoalkanol, which does not possess any inherent emulsifying properties, effectively stabilizes water-in-oil emulsions wherein a polyalkenyl succinic anhydride is employed as the emulsifying agent. The combination of an alkenyl succinic anhydride with a dialkylaminoalkanol produces a remarkably stable emulsion, far in excess of the stability which would be expected from the use of these compounds individually in such compositions.

The compositions of the present invention consist essentially of from 20% to about 45% by weight water phase and from 55% to about 80% by weight oil phase, the oil phase being essentially a mineral oil, containing a minor amount of (A) an oil-soluble compound having the formula R-CH-C CH C wherein R is a polyalkene group of from 30 to 500 carbon atoms, and (B) a dialkylaminoalkanol having the formula ice sirable constituents. For hydraulic fluids, lubricating oils are highly desired for the base oil and these include those having a high viscosity index, i.e., a viscosity index (Dean- Davis) of at least 80, preferably between and 100. Mineral oil fractions of this type are derived from paraffinic, naphthenic or mixed base crudes. They should also be in the lubricating oil range and have a viscosity, as determined at F., of from about 75 to 250 SUS, preferably between 100 and 150. A typical mineral oil base of this kind is a high viscosity index refined mineral lubricating oil having the following properties:

Gr., API", 60 32.2 Color, ASTM 1 Pour point, F. 5 Flash, F., COC 370 Fire, F 435 Viscosity, SUS at 100 F. 103 Viscosity index 93 Neutralization No. 0.01

In some emulsions, other lubricating oils, e.g., low viscosity index oils (2045 VI) may be used. These low viscosity index oils have a viscosity in the range from about 40 to 200 SUS at 100 F.

The oil soluble compound which is additive (A) is an alkenyl succinic anhydride. The alkenyl succinic anhydride can be prepared by alkylating maleic anhydride with a polyalkene from which the (R) group is derived and which functions as an oil-solubilizing aid. Examples of such polymers include polyethylene, polypropylene, polybutene, polyisobutylene, copolymers of ethylene/propylene, copolymers of ethylene/isobutylene, copolymers of ethylene/alpha-methyl styrene and the like. Monoalkylation of maleic anhydride with the above type olefinic polymers can be carried out by conventional means known in the art, preferably in the absence of a catalyst and at temperatures ranging from about 300 F. to 600 F., preferably between 350 F. and 450 F. The mole ratio of the polyalkene to maleic anhydride may vary from 1:1 to 1:10, preferably from 1:1 to 1:5, respectively. Particularly useful in the monoalkylation of maleic anhydride are polyisobutylenes in the molecular weight range of 3 00 to 5,000, preferably from 800 to 1,500.

Dialkylaminoalkanols (Additive B) which are contemplated for use in the present compositions as stabilizers, include those having two alike or dissimilar C alkyl groups, and a C alkanol group attached to the nitrogen atom. Preferred aminoalkanols are dialkylaminoethanols, e.g. dimethylaminoethanol, diisopropylaminoethanol and the like. A particularly advantageous stabilizing agent for use in conjunction with succinimide emulsifier is diethylaminoethanol.

The concentrations of additives (A) or (B) can vary from 0.05% to about 10% by weight of the total composition. Emulsions wherein additive (A) is present in the amount of from 1% to about 4% w., and additive (B) is present in the amount of from 0.05% to about 2% W. are preferred. The ratio of additive (A) to additive (B) can be from 40:1 to 1:2, preferably from 25:1 to 5:1.

In addition to the aforementioned compounds, other additives known to the art to perform a particular function or functions may also be incorporated into the waterin-oil emulsions of the present invention.

Excellent emulsion stability, especially under freezethaw conditions is obtained by the further addition of a water soluble alkylene glycol such as the lower alkylene glycols, i.e. C -C alkylene glycols, and particularly ethylene glycol. The alkylene glycol can be used in amounts of up to 25%, preferably from about 1 to 20% by weight based on the aqueous phase. Particularly preferred concentrations of alkylene glycol are in the range of about 5 to 15% by weight based on the aqueous phase.

In addition, it is preferred to use in the composition of the invention small amounts of from about 0.01% to about 2%, preferably from about 0.2% to about 1%, optional additives such as antioxidants, anti-corrosion agents, anti-wear agents, pour point depressants and the like to improve other characteristics of the emulsion. The antioxidants include the phenolic amines and/or metal thiophosphate compounds. The phenolic compounds are illustrated by the alkyl phenols, e.g., diand trialkyl phenols, for instance, 2,4- 2,3- 3,4- 2,6- and 3,5-diamylphenol; 2,4-dimethyl-6-tertiarybutylphenol; 2,6-ditertiarybutyl-4-methylphenol. The amines are illustrated by arylamines such as phenyl-alpha-naphthylarnine or phenylbeta-naphthylamine. The metal thiophosphates are illustrated by alkaline earth metal thiophosphates, e.g., calcium or zinc dimethyl cyclohexyldithiophosphate. Antiwear agents include sulfur-containing compounds such as oil-soluble polychloro hydrocarbyl thiocarbonate esters, e.g. polychloronaphtha methyl xant-hate marketed by Monsanto Chemical Co. under the name Santopoid S and characterized by sp. gr. 1.19 at 60/ 60 F., flash point 250 F., viscosity 63 cs. at 100 F., sulfur 11%, chlorine 31%. Thiocarbonates of this type are prepared by reacting a chlorinated petroleum naphtha with an alkali metal (potassium) alkyl dithiocarbonate. Other anti-wear agents include, for example, organic sulfides such as dibenzyl disulfide or dichlorodibenzyl disulfide, polyvalent metal dithiophosphates such as zinc or lead salts or C alkyl dithiophosphates, and polyvalent metal dithiocarbamates such as the zinc, cadmium or lead salts of N- or N,N- C alkyl substituted dithiocarbamic acid. The butyl or amyl substituted compounds are generally preferred. Suitable anti-corrosion agents, including vapor space inhibitors to protect against corrosion in vapor spaces of storage or other equipment, may be added. Vapor space inhibitors are generally effective in minor amounts, e.g., 01-03% W. and include, for example, volatile amines or C monocarboxylic acids. Exemplary compounds are n-hexylamine, dicyclohexylamine, piperidine, morpholine, 2,6- dimethylmorpholine, octanoic acid, monanoic acid, decanoic acid, and the like. Morpholine is a particularly preferred corrosion inhibitor.

Dyes and anti-foaming agent can be added to compositions of this invention. Oil-soluble dyes include naphthol yellow, Sandoz yellow, methylene blue, alizarin compounds, etc., while anti-foaming agents include silicone polymer (DC-200 fluids ranging in viscosity in centistokes from 100 to 1,000 at 250 C.) of silicone type A fluid made by Dow-Corning Co. and described in US. Pats. 2,563,588 and 2,662,055 and mixtures thereof. Suitable pour point depressants include for example, the polymeric Inethacrylates marketed by Rohm and Haas Co. under the name Acryloid 150.

Methods of preparing emulsions are well known in the art. In a typical procedure suitable for the preparation of the inventive compositions, a measured amount of water is slowly added to a mineral lubricating oil containing the oil soluble succinic anhydride emulsifying agent and the dialkylaminoalkanol stabilizer. The resulting mixture is passed through a colloid mill wherein it is agitated until a homogeneous emulsion is formed. Other means of emulsifying liquids, such as propeller or sonic agitation, are known to the art, and may likewise be employed.

The present compositions and the advantages thereof will be further described by means of the following examples which are given for illustrative purposes only; therefore, the invention in its broader aspects should not be limited thereto.

Composition A: Percent w. Diethylaminoethanol 0.5 Polyisobutenyl succinic anhydride 3.0 Mineral oil 56.0

Water chafin 40.5

In order to demonstrate the elfectiveness of dialkylaminoalkanols as emulsion stabilizing agents, three waterin-oil emulsions were prepared having the compositions shown in Table I. The emulsion stability of each composition was determined by measuring the volume percent of phase separation after storage for the lengths of time shown in Table II.

TABLE I Composition E F G Component:

Diethylaminoethanol, percent W 0.2

Polyisobutenyl succinic anhydride, percent W. Base fluid A, percent W 1 Base fluid A=38% Water blended With HVl mineral oil SUS 100 F.) containing 2.0% w. ethylene glycol. 0.6% zinc dithiophosphate 0.3% w. 2,6-di-t-butyl-4-methyl phenol, 0.1% \v. morpholine. 0.06% W. phenyl-alpha-naphthylamine and 0.018% w. yellow dye.

1 Balance.

TABLE II Phase separation percent V Time Free oil Oil rich Free Water Com osition;

Pi 46 days--. 3 35 FL... 20 minutes 56 29 15 G 104 days 3 0 1 Slight.

From the results shown in Table II it can be seen that Composition F containing diethylaminoethanol without polyisobutenyl succinic anhydride has extremely poor emulsion stability and would not be suitable as a hydraulic fluid. Likewise, the emulsion stability of Composition E is also unsatisfactory, since a considerable oil-rich phase was formed by the end of 46 days storage. In marked contrast Composition G containing both diethylamino ethanol and polyisobutenylsuccinic anhydride has excellent emulsion stability and gave no evidence of an oil-rich layer forming after 104 days of storage. It can, therefore, be seen that although diethylaminoethanol has no in herent emulsifying properties, it is extremely effective as an emulsion stabilizer when employed in combination with a succinic anhydride emulsifying agent.

To further demonstrate the stability of the water and oil emulsions of the invention, Composition G prepared in accordance with the invention was compared to a number of commercially available fire resistant hydraulic fluids by means of a 35-day storage stability test. In this test the samples are placed in an oven maintained at a temperature of F. for a period of 35 days.'At the end of the test period, the degree of separation into phases is reported as volume percent free oil, oil rich, water rich and free water, respectively. Test results are shown in Table III. The emulsifiers employed in Commercial Fluid 1 are identified in the footnote to Table III. The compositions of the remaining commercial fluids are not known.

TABLE III Oven, 35-Day Storage Stability Test at 140 F.

Phase separation,

Emulsion: .percent W. Composition G 3-0-2-1 Commercial Fluid 1 25010-7 Commercial Fluid 2 24-0-04 Commercial Fluid 3 19-0-0-8 Commercial Fluid 4 12032 Commercial Fluid 5 11-0-3-4 (ta) Values indiealte-free oil/oil wick/Water rich/free uii' Commercial Fluid- 1 40% W. Walter blended with HVl mineral oil (100 SUS 100' F.) containing 1.2% w. basic calcium sultonate, 1.2% w. basic calciium 019-22 al kyl silicylate as coemulsifier s.

The above data give a further indication of the improved emulsion stability obtained by practice of the present invention. While the emulsions of the prior art exhibited free oil separation to the extent of 11 to 25% by volume, the inventive composition had a free oil phase of only 3% at the end of the test period.

I claim as my invention:

1. A water-in-oil emulsion constituting from 20% to about 45% by weight water phase and from 55% to about 80% by weight oil phase, said oil phase consisting essentially of a mineral oil containing from 0.05% to 'by total composition weight each of (A) an oil soluble compound having the formula org-0:0

6 where R is a polyalkene of from 30 to 500 carbon atoms and (B) a dialkylaminoal'kanol having the formula wherein R and R are alike or dissimilar C alkyl groups and R is a C alkylene group.

2. The composition of claim 1 wherein R is polyisobutylene and (B) is a dialkylaminoethanol.

3. The composition of claim 2 wherein (A) is present in the amount of from 1% to about 4% w. and (B) is present in the amount of from 0.05 to about 2% w.

4. The composition of claim 3 wherein the (B) is diethylaminoethanol.

5. The composition of claim 1 wherein the water phase additionally contains from 1 to about 20% by weight based on the aqueous phase of a water soluble C C alkylene glycol.

References Cited UNITED STATES PATENTS 3,378,494 4/1968 Berger 25277 3,280,029 10/1966 Waldmann 25249.5

OTHER REFERENCES The Condensed Chemical Dictionary, pp. 330331. 7th ed. (1966), Reinhold Publ. Corp., New York.

LEON D. ROSDOL, Primary Examiner H. A. PITLICK, Assistant Examiner US. Cl. X.R. 

